1. Field of the Invention
The present invention relates to a method for producing a thick film photoresist pattern.
2. Related Art
Photofabrication is now the mainstream of a microfabrication technique. Photofabrication is a generic term describing the technology used for manufacturing a wide variety of precision components such as semiconductor packages. The manufacturing is carried out by applying a photoresist composition to the surface of a processing target to form a photoresist layer, patterning this photoresist layer using photolithographic techniques, and then conducting chemical etching, electrolytic etching, and/or electroforming based mainly on electroplating, using the patterned photoresist layer (photoresist pattern) as a mask.
In recent years, high density packaging technologies have progressed in semiconductor packages along with downsizing electronics devices, and the increase in package density has been developed on the basis of mounting multi-pin thin film in packages, miniaturizing of package size, two-dimensional packaging technologies in flip-tip systems or three-dimensional packaging technologies. In these types of high density packaging techniques, connection terminals, including protruding electrodes (mounting terminals) known as bumps that protrude above the package or metal posts that connect rewirings extending from peripheral terminals on the wafer with the mounting terminals, are disposed on the surface of the substrate with high precision.
In the photofabrication as described above, a photoresist composition is used, and chemically amplified photoresist compositions containing an acid generator have been known as such a photoresist composition, (see Patent Documents 1, 2 and the like). According to the chemically amplified photoresist composition, an acid is generated from the acid generator upon irradiation with radiation (exposure) and diffusion of the acid is promoted through heat treatment, to cause an acid catalytic reaction with a base resin and the like in the composition resulting in a change to the alkali-solubility of the same.
Also, the photoresist compositions used in the photofabrication described above are typically chemically amplified positive-type photoresist compositions for a thick film (see Patent Document 3 and the like). The chemically amplified positive-type photoresist compositions for a thick film are employed for forming bumps or metal posts in plating processes, for example. For example, a thick photoresist layer of about 20 μm is formed on a support, and the photoresist layer is exposed through a predetermined mask pattern and then developed to produce a resist pattern in which portions for forming bumps or metal posts are selectively removed (stripped). Then, bumps or metal posts can be formed by embedding a conductor such as copper into the removed portions (resist-free portions) using plating, and then removing the surrounding residual photoresist pattern.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. H9-176112
Patent Document 2: Japanese Unexamined Patent Application, Publication No. H11-52562
Patent Document 3: Japanese Unexamined Patent Application, Publication No. 2010-185986